1. Field of the Invention
The present invention is for a street sweeper drag shoe used in a sweeping operation, and more particularly, pertains to a street sweeper drag shoe of cast austempered ductile iron with a deflection plate and a skirted contact skid utilized for accomplishing substantially complete dirt and debris collection by a street sweeper.
2. Description of the Prior Art
Prior art street sweeper drag shoes have uniformly been designed as a shaped linear piece of metal. A street sweeper drag shoe performs a critical containment function in street sweeping machines. A rotary broom is mounted on a supporting axle and the bottom regions of the rotary broom align in close proximity to the inner surfaces of opposing sweeper drag shoes. Sweeper drag shoes define the boundary of the sweeping area, and can serve to mount skirted panels surrounding the lower edges of the rotary broom and sealingly contact the road surface as the mobile street sweeper accomplishes its sweep. One drawback of this configuration is that a wedge of dirt and debris rapidly builds up in front of the rotary broom during its sweeping action, and this wedge, like a wedge of water, builds and drifts to the ends of the rotary broom. The typical sweeper drag shoe is intended to form a seal on either end of the lower edges of the rotary sweeper broom to contain the dirt wedge. The current art sweeper drag shoe design allows dirt and debris to escape beneath the sweeper drag shoe, particularly on uneven surfaces, resulting in an incomplete collection of dirt and debris at the edges of the sweeping path.
Prior art drag shoes often required time-consuming fabrication and assembling, adding to the cost and effort required to produce a suitable sweeper drag shoe. Yet another drawback of prior art sweeper drag shoes is the use of carbide wear plates, which are intended to prolong the wear and use of the sweeper drag shoes. The use of carbide wear plates, while being partly successful in prolonging drag shoe life, often caused either cosmetic or structural damage to the roadway surface, as the weight of the drag shoes and other attendant structures is concentrated at the points of contact between the roadway and the carbide wear plates. The carbide wear plates would often outlast the contact skid of the drag shoe which was being protected in the area whereat the contact skid of the drag shoe would be subjected to abrasion by sand, rocks, stones and the like which would abrasively impinge the contact skid of the drag shoe during sweeping operations. However, sealing of or near the lower surface of the drag shoe with the use of carbide wear plates carried the lower surface of the drag shoe, i.e., the contact skid, just slightly above the roadway surface, leaving the carbide wear plates, which exhibit less contact than the contact skid of the drag shoe, as the actual sealing barrier instead of the contact skid of the drag shoe. Carbide wear plates, some of which are replaceable, can encounter road anomalies which can strain the connecting hardware and cause the carbide wear plates to be sheared from the underside of the contact skid.
What is needed is simply a fabricated sweeper drag shoe that has an improved contact skid to maximize roadway contact; that has an improved rotary broom seal along the forward portion of the sweeper drag shoe; that redirects the broom bristles so as to collect and redirect the escaping wedge of dirt and debris which exits from beneath the sweeper drag shoe; that is extremely durable and that otherwise overcomes the shortcomings of previous sweeper drag shoes.
The present invention provides a street sweeper drag shoe of cast austempered ductile iron having an improved forward portion seal and an improved drag shoe to surface seal, and which provides means to contain and redirect the escaping wedge portion of dirt and debris.